My EP739 never got to the point where it actually shutdown due to overheating, but the root-cause may be the same. First thing you must do is clean out any dust and debris that may be restricting airflow. If that doesn't help then read-on...My Optoma EP739 started exhibiting color-banding and strong color shift after years of great service. After trying other suggestions that didn't work, here is the FIX for my unit. I have not seen this posted anywhere else.

Problem: After 10-20 minutes of use, color-banding and then a strong shift to purple/green with almost no red. If the unit is turned off for 5-10 minutes to cool and then powered-up again the problem goes away, only to come back in another 10-20 minutes. Enabling the "High Altitude" setting in the Setup Menu helped for a while (a week or two) since it forces the main cooling fan run at high speed always, but then the problem re-appeared.

Reason: Overheating. The electronics are overheating. Like several people have suggested: First step: Open the unit up and blow-out/vacuum all of the accumulated dust. Assure BOTH fans (there is a small drum blower directly cooling the lamp and a larger regular fan that circulates air through the entire unit) are operating and clear of debris.

Once you have done that, then look for the REAL issue. With the front panel (i.e.the panel with the hole for the lens) removed and looking into the projector from the front examine the metal heat shield on the right side above the lamp. In my unit, because of years of service and heat, the aluminum lamp housing had deformed slightly, tilting this sheet metal heat shield directly INTO the air stream from the fan. This restricts the airflow enough to reduce cooling capacity. This metal shield should be high enough above the lamp to be TOUCHING the plastic case. If it is bent down and is halfway into the air stream then it restricting the exhaust airflow, causing the overheating.

Fix: Bend the heat shield back up so that it is not in the exhaust airflow. It must be ABOVE the airflow, protecting the plastic case from the heat of the lamp. This simple remedy fixed the issue for me. My projector has been running 2-3 hours a day for 10 days now with no banding issues at all. That's it. Simple fix.

My unit never got to the point of actually shutting down due to overheating, but your problem may be related to what I experienced: A bent lamp heat shield.My Optoma EP739 started exhibiting color-banding and strong color shift after years of great service. After trying other suggestions that didn't work, here is the FIX for my unit. I have not seen this posted anywhere else.

Problem: After 10-20 minutes of use, color-banding and then a strong shift to purple/green with almost no red. If the unit is turned off for 5-10 minutes to cool and then powered-up again the problem goes away, only to come back in another 10-20 minutes. Enabling the "High Altitude" setting in the Setup Menu helped for a while (a week or two) since it forces the main cooling fan run at high speed always, but then the problem re-appeared.

Reason: Overheating. The electronics are overheating. Like several people have suggested: First step: Open the unit up and blow-out/vacuum all of the accumulated dust. Assure BOTH fans (there is a small drum blower directly cooling the lamp and a larger regular fan that circulates air through the entire unit) are operating and clear of debris.

Once you have done that, then look for the REAL issue. With the front panel (i.e.the panel with the hole for the lens) removed and looking into the projector from the front examine the metal heat shield on the right side above the lamp. In my unit, because of years of service and heat, the aluminum lamp housing had deformed slightly, tilting this sheet metal heat shield directly INTO the air stream from the fan. This restricts the airflow enough to reduce cooling capacity. This metal shield should be high enough above the lamp to be TOUCHING the plastic case. If it is bent down and is halfway into the air stream then it restricting the exhaust airflow, causing the overheating.

Fix: Bend the heat shield back up so that it is not in the exhaust airflow. It must be ABOVE the airflow, protecting the plastic case from the heat of the lamp. This simple remedy fixed the issue for me. My projector has been running 2-3 hours a day for 10 days now with no banding issues at all. That's it. Simple fix.

If you contact Optoma and they have the part available then, yes you can fix it yourself. You have to be good at taking things apart and remembering how they go back together. Changing the color wheel assembly is not that hard.

The solution from bjwjb posted on Dec 30, 2009 is absolutely correct:"There is a piece on the bulb cover panel that you take off in order to change the bulb that fits down inside the bulb assembly when you put the panel back on. The bulb cover panel and the part of the panel that goes down into the bulb assembly must be present or the projector will not power up (there will be no lights either)." I would add to that once the cover is placed back, but before the screws of the bulb cover are tightened, firm pressure should be place on on the bulb cover panel on the spot placed where the plastic protrusion (a plastic "stick" about 1.5 inches long that fits into a void in the bulb assembly) goes into the bulb assembly. You should/may hear a "click", indicating that the protruding plastic piece has been fully inserted into the bulb assembly and makes contact with whatever contraption is inside the assembly to enable power-up. If no pressure is exerted the plastic protusion may not extend down far enough to make contact to enable power-up. In such case the bulb cover panel may be slightly bulging in the location of the protrusion. You would still be able to tighten the bulb cover panel screws, because the plastic is flexible. In such case you may find that the screw closest to the location of the plastic protrusion may need pushed in more. In this condition, even though you may think the cover is properly placed, the plastic protrusion is not fully inserted and does not make contact and there are no lights or power. Just take of the bulb cover panel place it back following the instructions above.

I had already disassembled my projector and was ready to bring it in for service when I did an internet search and saw the advice from bjwjb. Thanks very much!

hi,
check the resolution your have selected in the laptop. if u are using windows
right click on the desktop select properties and select settings. in setting window reduce the resolution and apply it. close the window and then try again.
If then also problem remains purchase a good quality VGA cable
ok